Add host function for direct logging

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - Lowercase model name before invoking for hypermode hosted models [#221](https://github.com/gohypermode/runtime/pull/221)
 - Improve HTTP error messages [#222](https://github.com/gohypermode/runtime/pull/222)
+- Add host function for direct logging [#224](https://github.com/gohypermode/runtime/pull/224)
 
 ## 2024-06-03 - Version 0.8.2
 

graphql/datasource/source.go

@@ -68,7 +68,11 @@ func (s Source) callFunction(ctx context.Context, callInfo callInfo) (any, []res
 	ctx = context.WithValue(ctx, utils.ExecutionIdContextKey, executionId)
 	ctx = context.WithValue(ctx, utils.PluginContextKey, info.Plugin)
 
-	// Create output buffers for the function to write logs to
+	// Also prepare a slice to capture log messages sent through the "log" host function.
+	messages := []utils.LogMessage{}
+	ctx = context.WithValue(ctx, utils.FunctionMessagesContextKey, &messages)
+
+	// Create output buffers for the function to write stdout/stderr to
 	buffers := utils.OutputBuffers{}
 
 	// Get a module instance for this request.
@@ -92,8 +96,9 @@ func (s Source) callFunction(ctx context.Context, callInfo callInfo) (any, []res
 		Buffers:     buffers,
 	}
 
-	// Transform error lines in the output buffers to GraphQL errors
-	gqlErrors := transformErrors(buffers, callInfo)
+	// Transform messages (and error lines in the output buffers) to GraphQL errors
+	messages = append(messages, utils.TransformConsoleOutput(buffers)...)
+	gqlErrors := transformErrors(messages, callInfo)
 
 	return result, gqlErrors, err
 }
@@ -238,8 +243,7 @@ func transformValue(data []byte, tf *fieldInfo) (result []byte, err error) {
 	return buf.Bytes(), nil
 }
 
-func transformErrors(buffers utils.OutputBuffers, ci callInfo) []resolve.GraphQLError {
-	messages := utils.TransformConsoleOutput(buffers)
+func transformErrors(messages []utils.LogMessage, ci callInfo) []resolve.GraphQLError {
 	errors := make([]resolve.GraphQLError, 0, len(messages))
 	for _, msg := range messages {
 		// Only include errors.  Other messages will be captured later and

hostfunctions/hostfns.go

@@ -22,6 +22,7 @@ func Instantiate(ctx context.Context, runtime *wazero.Runtime) error {
 	b := (*runtime).NewHostModuleBuilder(hostModuleName)
 
 	// Each host function should get a line here:
+	b.NewFunctionBuilder().WithFunc(hostLog).Export("log")
 	b.NewFunctionBuilder().WithFunc(hostExecuteGQL).Export("executeGQL")
 	b.NewFunctionBuilder().WithFunc(hostInvokeClassifier).Export("invokeClassifier")
 	b.NewFunctionBuilder().WithFunc(hostComputeEmbedding).Export("computeEmbedding")

hostfunctions/log.go

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2024 Hypermode, Inc.
+ */
+
+package hostfunctions
+
+import (
+	"context"
+	"hmruntime/logger"
+	"hmruntime/utils"
+
+	wasm "github.com/tetratelabs/wazero/api"
+)
+
+func hostLog(ctx context.Context, mod wasm.Module, pLevel uint32, pMessage uint32) {
+
+	var level, message string
+	err := readParams2(ctx, mod, pLevel, pMessage, &level, &message)
+	if err != nil {
+		logger.Err(ctx, err).Msg("Error reading input parameters.")
+	}
+
+	// write to the logger
+	logger.Get(ctx).
+		WithLevel(logger.ParseLevel(level)).
+		Str("text", message).
+		Bool("user_visible", true).
+		Msg("Message logged from function.")
+
+	// also store messages in the context, so we can return them to the caller
+	messages := ctx.Value(utils.FunctionMessagesContextKey).(*[]utils.LogMessage)
+	*messages = append(*messages, utils.LogMessage{
+		Level:   level,
+		Message: message,
+	})
+}

logger/logwriter.go

@@ -41,7 +41,7 @@ func (w logWriter) Write(p []byte) (n int, err error) {
 
 func (w logWriter) logMessage(line string) {
 	l, message := utils.SplitConsoleOutputLine(line)
-	level := parseLevel(l)
+	level := ParseLevel(l)
 	if level == zerolog.NoLevel {
 		level = w.level
 	}
@@ -52,7 +52,7 @@ func (w logWriter) logMessage(line string) {
 		Msg("Message logged from function.")
 }
 
-func parseLevel(level string) zerolog.Level {
+func ParseLevel(level string) zerolog.Level {
 	switch level {
 	case "debug":
 		return zerolog.DebugLevel

utils/context.go

@@ -9,3 +9,4 @@ type contextKey string
 const ExecutionIdContextKey contextKey = "execution_id"
 const PluginContextKey contextKey = "plugin"
 const FunctionOutputContextKey contextKey = "function_output"
+const FunctionMessagesContextKey contextKey = "function_messages"